Waterfalls as geological heritage sites

Waterfalls are unique natural objects. Their physical (height, width, cliff angle) and hydrological (water discharge) parameterscan be measured easily to allow judgements about their uniqueness. However, waterfalls are interesting not only from the point of viewof physical geography, but also geology. Generally, the uniqueness of geological heritage sites is determined by their information value.Waterfalls offer, at least, five kinds of information about the geological environment. Firstly, they characterize the geological activity ofsurficial streams with the steep longitudal profile. This occurs, first of all, in the forms of cliff erosion via its undercutting with periodicrockfalls, gradual detachment of sedimentary particles from the waterfall face, stream cutting at the very edge of the cliff, and formationof potholes at the base of waterfall because of hydraulic power and mechanical destruction by transported sedimentary load. Secondly,waterfalls offer some information about geological phenomena, which control their spatial occurrence. Thirdly, peculiar geologicalfeatures can be exposed in cliffs and adjacent slopes of the river valley. Fourthly, the formation of waterfall and the subsequent landformchanges is linked to the engineering-geological properties of rock massifs, including rock strength, fracturing, etc. Fifthly, studies ofancient waterfalls permit to obtain a very special information about the geological history of the given region (for instance, aboutcatastrophic events such as outflows from glacial lakes). The uniqueness of geological information represented in a given waterfall, and,consequently, the rank of the latter, do not depend completely on its physical and hydrological parameters. On the one hand, a largerwaterfall exhibits stronger geological activity of surficial streams. But, on the other hand, rare geological objects can be exposed in cliffsof even very little waterfalls. Aesthetic attractiveness of waterfalls may diminish their importance as sources of the new knowledge, butthe same attractiveness stimulates tourists to visit these sites. By example of waterfalls, it becomes clear that the concept of geodiversityextends far beyond geological environment itself. This fact, however, does not mean improvements of the available approaches for thenumerical assessment of geodiversity. In Russia, it is possible to outline a number of territories, where waterfalls diversify the regionalgeological heritage substantially. A typical example is the mountainous part of the Republic of Adygea in the Northern Caucasus, wherea number of waterfalls are known from the unique centre of geodiversity.

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